1. Field of the Invention
The present invention relates to a ferrule heating apparatus for heating a ferrule when an optical fiber and a ferrule are adhered each other using a thermosetting adhesive agent by inserting one end side of the optical fiber into an optical fiber insertion through hole being provided on the ferrule. More specifically, the present invention relates to a ferrule heating apparatus in which a ferrule heating unit for heating the ferrule and a temperature control unit for controlling the temperature of this ferrule heating unit are mutually separated.
2. Description of the Related Art
Previously, a ferrule heating apparatus has been disclosed in Japanese Patent Application No. 2002-077022. FIG. 1 is a front view showing a schematic constitution of the previously disclosed ferrule heating apparatus 100. FIGS. 2A and 2B are views showing a holder 102 provided in the ferrule heating apparatus 100 for housing ferrules in which optical fibers are inserted for heating. FIG. 2A is a plan view of the holder 102, and FIG. 2B is a cross-sectional view taken along the II—II line in FIG. 2A.
FIG. 3 is an enlarged cross-sectional view showing a state of aligning a ferrule into a housing position, where the optical fibers are inserted into ferrule housing holes 104 provided in a plurality on the holder 102.
The ferrule heating apparatus 100 includes the holder 102 for housing and aligning ferrules 106 being in a state that a tip side (one end side) of an optical fiber 110 is inserted into an optical fiber insertion through hole 108 (see FIG. 3) provided on the ferrule 106, heating means 112 for heating one side-face side (a lower face side) of the holder 102, holder heating unit moving means 116 for moving a holder heating unit 114 provided on the heating means 112 approximately in the vertical direction (the AR direction, the arrow, as shown in FIG. 1) such that the holder heating unit 114 approaches/contacts (in the +Z direction) or moves away (in the −Z direction) to/from the holder 102, and optical fiber retaining means 118 for retaining the numerous optical fibers 110 extending in the upper direction (the +Z direction) from the ferrules 106 which are housed and aligned in the holder 102. Moreover, the holder 102 and the optical fiber retaining means 118 are supported by base frames 120.
The holder 102 is made of a member having good heat conductance such as metal, and is formed into a rectangular solid shape as shown in FIGS. 2A and 2B. The holder 102 is fixed to the base frames 120 such that two faces having the largest areas among the six faces of this rectangular solid are set horizontal (in the X-Y direction). Moreover, the base frames 120 are disposed on upper faces of a work table, for example.
Of the holder 102, a lower side face among the two faces having the largest areas constitutes a holder heating unit contact surface 122 for contacting the holder heating unit 114, and the plurality of the ferrule housing holes 104 for housing and aligning the ferrules 106 are pierced approximately perpendicularly to the holder heating unit contact surface 122. The layout of the ferrules are set as 12 pieces×2 lines=24 pieces, for example. As shown in FIG. 3, the ferrule housing hole 104 has a constitution in which a small-diameter hole portion 104A on a lower side and a large-diameter hole portion 104B on an upper side are formed coaxially.
Next, description will be made regarding a state where the optical fiber 110 is inserted into the ferrule 106 and a state where the ferrule 106 after insertion of the optical fiber 110 is housed and aligned in the ferrule housing hole 104 provided on the holder 102.
As shown in FIG. 3, a bare optical fiber portion (a tip portion) 110A of the optical fiber 110, where a covering on one end side is removed and the bare optical fiber is thereby exposed, is inserted into the fiber insertion hole (the through hole) 108 of the ferrule 106 in which a thermosetting adhesive agent is filled in advance. The tip portion 110A of the optical fiber 110 slightly protrudes out of the fiber insertion hole 108 on a tip portion (a tip face) side of the ferrule 106. This slightly protruding portion of the tip portion 110A is set slightly inside from the holder heating unit contact surface 122 of the holder 102. Here, the end face of the tip portion 110A of the optical fiber 110 slightly protruding out of the end face of the ferrule 106 is polished in a subsequent step.
On a base end side of the ferrule 106, i.e. on the side of the extending (stretched) optical fiber 110 without removing the covering (the opposite side to the protrusion of the bare optical fiber portion 110A), there is provided a metal flange 124 so as to envelop the optical fiber 110.
As described above, the ferrule 106, in which the bare optical fiber portion 110A is inserted on the tip side, and in which the metal flange 124 is provided on the base end side, is housed and aligned in the housing hole 104 including the small-diameter portion 104A and the large-diameter portion 104B such that the tip side of the ferrule 106 is positioned on the holder heating unit contact surface 122 side while the metal flange 124 on the based end side is positioned on the opposite side to the holder heating unit contact surface 122.
As shown in FIG. 1, the heating means 112 is configured by the vertically movable holder heating unit 114 for heating the holder 102 by contacting the holder heating unit contact surface 122, i.e. the lower face, of the holder 102, and a heater main body (a temperature control unit) 126 including a controller for controlling a temperature of this holder heating unit 114 as in a conventional example and a timer for regulating heating time.
The holder heating unit 114 includes an upper face, which contacts the holder heating unit contact surface 122 being formed on the lower face of the holder 102, as a holder contact surface 128. The holder contact surface 128 is formed into a planar shape and is set approximately horizontal so that the holder contact surface 128 can contact the entire holder heating unit contact surface 122. Moreover, the holder contact surface 128 is formed into an approximately rectangular shape, and the area thereof is formed into dimensions equal to or slightly larger than the holder heating unit contact surface 122 provided on the holder 102.
Meanwhile, the holder heating unit 114 moves in the vertical direction (in the direction indicated with the arrow AR in FIG. 1) by use of the holder heating unit moving means 116. Accordingly, the holder contact surface 128 is regulated to approach, contact, or move away from the holder heating unit contact surface 122 provided on the lower face of the holder 102.
The optical fiber retaining means 118 includes a rotating member 130 of a pipe shape which is set horizontal and freely rotatable, and an elastic member 134 made of a sponge (or other sponge-like synthetic resin, rubber or the like) which includes a plurality of nicks 132 for sandwiching and thereby holding the optical fibers 110. Both end portions of the rotating member 130 are respectively supported by the base frames 120.
The rotating member 130 is provided approximately parallel to the longitudinal direction of the holder 102 and also horizontally, and is disposed in a position above the holder 102.
Next, description will be made regarding an operation of the ferrule heating apparatus. First, in a state where the holder 102 and the holder heating unit 114 are separated vertically from each other while a power source of the heater is turned off, the plurality of ferrules 106, in which the optical fibers 110 are inserted, are respectively housed and aligned one-by-one in the plurality of ferrule housing holes 104 provided on the holder 102 as shown in FIG. 3. Upon this alignment, the optical fibers 110 extending from the ferrules 106 are retained by the optical fiber retaining means 118 as shown in FIG. 1. In this way, it is possible to avoid a trouble such as entanglement among the optical fibers 110.
Moreover, after housing and aligning the plurality of ferrules 106 in the housing positions in the respective housing holes 104, the holder heating unit 114 is moved upward by use of the holder heating unit moving means 116, whereby the upper face of the holder heating unit 114 (the holder contact surface 128) and the lower face of the holder 102 (the holder heating unit contact surface 122) are allowed to contact each other. In this state, the power source of the holder heating unit 114 is turned on, so that the holder 102 and the ferrules 106 are heated for a predetermined time period (about 30 minutes, for example) at a predetermined temperature (about 85° C., for example). In this way, the thermosetting adhesive agent existing between the ferrules 106 and the optical fibers 110 are hardened so that the ferrules 106 and the optical fibers 110 are adhered integrally.
After adhesion, the power source of the holder heating unit 114 is turned off, and the holder heating unit 114 is moved downward to be separated from the holder 102 by use of the holder heating unit moving means 116. Subsequently, the ferrules 106 which are housed and aligned in the housing holes 104, and the optical fibers 110 retained by the optical fiber retaining means 118 are taken away, and then the next ferrules 106 and others for adhesion are housed and aligned in the housing holes 104 in the same way.
Adhesion of the ferrules 106 and the optical fibers 110 is continuously performed by repeating the above-described operation.